One prior catalyst for dehydrogenating oxygen-containing derivatives of cyclohexane is known to comprise nickel as an active component, as well as promoters, viz., copper, chromium and sodium sulphate, on an inert contact carrier (cf. U.S. Pat. No. 2,640,084, class 260/621, 1953). However, this catalyst features but low capacity in dehydrogenating monooxygen cyclohexane derivatives, such as cyclohexanol or cyclohexanone, i.e., the productivity for the end product, viz, phenol is not more than 0.15 kg per liter catalyst at 350.degree. C.
Moreover, when dehydrogenating cyclohexane derivatives containing more than one oxygen atom per molecule in the presence of the abovesaid catalyst, a secondary process, i.e., dehydration occurs to a substantial extent. As a result, the selectivity of the catalyst involved with respect to the desired dihydric phenols in, say, dehydrogenating cyclohexanediol-1,2 into pyrocatechol, is as low as 15 to 20 percent.
One more catalyst for dehydrogenating oxygen-containing derivatives of the cyclohexane series having the following general formula ##STR2## where R.sub.1 is either hydrogen or alkyl C.sub.1 -C.sub.4,
R.sub.2 and R.sub.3 are radicals having either the same or different values --H, --OH, .dbd.O, provided that R.sub.2 and R.sub.3 cannot both be hydrogen, PA1 metal of Group VIII of the Periodic System--2 to 20 PA1 tin--2 to 30 PA1 inert carrier--to make up 100 percent PA1 R.sub.2 and R.sub.3 are radicals having either the same or different values --H, --OH, .dbd.O, provided that R.sub.2 and R.sub.3 cannot both be hydrogen atoms, PA1 nickel--15 to 55 PA1 tin--0.2 to 1.95 PA1 inert carrier--84.8 to 43.05,
R.sub.1, R.sub.2, R.sub.3 being linked to different carbon atoms of the ring into the corresponding ketones and phenols, said catalyst containing, as an active component, a metal of Group VIII of the periodic system, such as nickel, as well as a promoter, i.e., tin and an inert contact carrier, i.e., silica. The atomic ratio of the metal of Group VIII and tin in this catalyst ranges within 1.7:1 to 15:1, respectively. The weight percentage content of the aforesaid catalyst components lies within the following limits:
(cf. H. E. Swift, J. E. Bozik, J. Catal, v.12, p.5 /1968/; U.S. Pat. No. 3,580,970, class 260-621H, 1971).
The above catalyst has the disadvantage of having only a low capacity with respect to ketones and phenols and in being insufficiently stable. Thus, for instance, the productivity for phenol of an optimum-composition nickel-tin catalyst (atomic ratio of Ni:Sn being 2.5:1) supported on silica equals 1.3 kg/l at 375.degree. C., whereas in eight hours the productivity drops below 1.0 kg/l (cf. FIG. 4 of the afore-cited U.S. Patent). Similar results have been obtained in the study by M. Masai et al. (J. Catal, v.38, p.128, 1975), i.e., the initial productivity of a nickel-tin catalyst (Ni:Sn ratio being 2.5:1) in cyclohexanone dehydrogenation at 400.degree. C. equals 1.0 kg/l, whereas in eight hours it drops to only 0.6 kg/l.
Selectivity of the known catalyst in dehydrogenating mono-oxygen derivatives of cyclohexane into phenol is reasonably high, amounting to 98 percent, whereas the selectivity for ketones is rather low. Thus, when dehydrogenating cyclohexanol into cyclohexanone the abovesaid selectivity is as low as 50 percent (cf. op. cit. by H. E. Swift and J. E. Bozik). Especially low is the selectivity of the known catalyst when it is applied for dehydrogenating polyfunctional oxygen-containing derivatives of the cyclohexane series into the corresponding polyhydric phenols. For instance, when dehydrogenating cyclohexandiol-1,2 at 330.degree. C. and below, the selectivity in terms of the desired pyrocatechol is as low as 30 percent, whereas dehydrogenation process occurring at a temperature above 330.degree. C. are accompanied by vigourously running secondary reactions, which result in fast deactivation of the catalyst.
A process for dehydrogenating oxygen-containing derivatives of the cycolohexane series of the aforesaid general formula (feed stock) into the corresponding cyclic ketones and/or phenols is known to comprise contacting such oxygen-containing derivatives of the cyclohexane series with the nickel-tin catalyst of the abovesaid composition at a temperature of from 375.degree. to 400.degree. C. in the presence of hydrogen taken in a sixfold molar excess amount with respect to the feed stock (cf. H. E. Swift, J. E. Bozik, J. Catal., v.12, p.5, 1968; U.S. Pat. No. 3,580,970, class 260-621H, 1971).
The afore-noticed disadvantages of the known nickel-tin catalyst account for the disadvantages of a process for dehydrogenating oxygen-containing compounds of the cyclohexane series using said catalyst. Thus, e.g., use of a low-capacity catalyst results in low output of the entire dehydrogenation process, while inadequate stability of the catalyst affects adversely all characteristics of the process, that is, conversion of the starting materials, selectivity and yield of the end products with time, and is responsible for a necessity of periodically stopping the dehydrogenation process for regenerating the catalyst.
With a view to improving the stability of the known catalyst, its composition incorporates additionally such a deficient and costly element as platinum, as well as chromium and sodium sulphate. However, this badly affects the catalyst capacity and the productivity of the whole process, which is as low as 0.2 kg/l per hour.